Levers and Equivalents.
which can be easily proved by the levers shewn below. Generally,
then, for toothed gearing with wheel and axle,
......... ., ,' , .W followers handle rad.
Mech. Adv. = -j-.------ x-------~~
P drivers barrel rad.
the wheels being estimated by teeth, radius, or diameter.
Belting is a substitute for toothed gearing, as shewn in the
Diagram, a crossed belt giving the same direction of motion
j&s Ane pair of wheels. N.B.,If speeds only are to be reckoned,
the wheel andfaxle does not enter into the calculation.
T}ie Brock arid Tackle (Fig. 439).~Neglectirig friction)
the cord has the same tension throughout, and there are (in the
case shewn) six pulls on the weight, each equal to P.
,, , AJ W 6 No. of cords
^ .,% .Meet. Adv. ~ =. - or generally == ._
v...... ' ' ' ' W ' '2
;J 'In-any -movable pulley M, p- = - because W only rises half
of P, as shewn. (Seep. 741.)